People were never seriously interested in extending their lives. I submit that there's a pretty easy, macabre (to most) way to go about it:
Monoclonal antigen-free body farms. Grow human bodies in labs -- farmed donor bodies -- and get good at head transplants.
This cures most cancers, most diseases, skipping the complicated molecular biology we've yet to solve for.
Literally replace your whole body as it ages. You can renew the thymus (big!), circulatory, pulmonary system, etc. It would have a rejuvenating affect on the brain. You'd probably give humans 150-year lifespans with it. Be able to run marathons in your 70's.
We'd suck at head transplants for decades (reducing patient outcomes in the initial period), but over time could probably get quite good at it. Initial patient populations could be recruited from terminal cancer patients, where the cancers have not spread to the blood or brain tissues. Survival rates would be low, and a lifetime of paralysis would likely be the penalty for the first decade or so of patients. But in time, we'd get better. Eventually to the point where it was no longer an emergency procedure, but a preventative maintenance measure.
The ancillary tech that would spring up from this would be in the BCI domain and we'd start getting good at modeling brain states. A whole industry of related organismal-level biotech advances would arise, propelling us forward like a new space age (or AI wave, to reference a current trend of advances).
There are crazy other things you could do - race and gender changes, better than natural genes and performance (VO2 max etc) enhancements, transgenic stuff, etc. Why limit ourselves to our previous limitations?
In 200 years we could conceivably move human thoughts onto silicon and stop dying. Too late for us with present day "life extension" / "health span" prognosis, so nobody is trying.
But it's "icky" and you'd get an even worse reaction than artists take to AI art or certain greens take to nuclear. The "people should die" folks raise their pitchforks, as do the incredibly religious. It's a very tough pill to swallow.
It angers me, because it's pretty low hanging fruit. You could grow bodies as vegetables without brains. Cut them off in development genetically and surgically. Innervate and artificially grow the bodies in advanced farms that keep their muscles moving, their hormones and limbic systems pumping, etc.
If I make a billion dollars I'll put everything into it. I want to live 150 years, and I want everyone else to as well. It's way more important to me than buying stuff or collecting "experiences".
As it stands, there's little point to anything we do (despite the fact none of us behave this way). Our experiences and enjoyment are short-lived dopamine hits to decaying neural networks, which on the geologic time scale, are pathetic little flashes that will never be noticed or remembered. When our brain cells bleb and desiccate, they won't remember all the good times we had or money we spent.
My perspective is we're all already dead. We may as well be holograms of our machine descendants playing out historical recreations.
Anyway, we could solve this if we put ourselves to it. I've yet to meet anyone else that's so gung-ho about it. I just think we're too early. And to this decaying neural network, it's kind of a horror to watch how others deal with the fact.